Missed those deals. Looks like the price was lowered and they got snapped up.

As for the connection:
hpiracing is, well, HPI Racing. Their shipping address is the same as HPI's US headquarters address.
buburacing seller information shows Yuko Watanbe in emails sent by eBay. Google says Yuko is the assistant to President/CEO of HPI.

i have a cart full of stuff for bubu and they won't give me a total since Saturday. it sucks because now that the other HPI seller is saying they combine, i can get a better deal there on top of an additional model that is not listed with bubu, but when you have a cart and request a total, you have to commit to buy. well now one of the models is on the "last one" in my cart, i have committed to buy but like i said, no total given.

do some sellers have a thing that automatically does this? because it has always seemed almost automatic in the past.

EDIT: as of yesterday, 1/1, they finally totaled the invoice and shipping is $35 for four models. was $38. haha. i sent them a message saying their shipping info says add'l items are $2.50 and asked them to please advise.